The present invention relates generally to packages for fresh red meat. Particularly, this invention is directed to the packaging of food products such that the packaged product may be maintained in one condition under certain circumstances and then converted to another condition. Specifically, packages in accordance with the present invention provide for distribution of a packaged product in a low oxygen environment and for introduction of oxygen to the product surface at a supermarket or other retail outlet. Such introduction of oxygen is achieved either by permeation of oxygen through a film in contact with the product surface or through an exchange of atmospheric oxygen with a low oxygen gaseous atmosphere contained around the product.
While a wide variety of food products can be packaged in accordance with the teachings of this invention, it is particularly advantageous in connection with the packaging of fresh red meat such that the meat may be transported in a low oxygen atmosphere, that is, preferably 0.5% O.sub.2 or less, most preferably 0.05% O.sub.2 or less, and then caused to bloom when it reaches a supermarket by exposure to oxygen.
Historically, large sub-primal cuts of meat have been butchered and packaged in each supermarket. This, however, can be inefficient and result in certain undesirable additional costs. For example, all cuts from a large sub-primal must be sold at once. Instead it would be preferable to permit the meat to be butchered and packaged at a central facility which benefits from economies of scale and thereafter shipped to individual supermarkets such as is done, for example, with many poultry products.
In the past, the goal of central fresh red meat processing has not been achievable because most consumers prefer to buy meat which is reddened in color as a result of exposure to oxygen. However, the meat maintains its reddened color for approximately one to three days and, thereafter, turns a brown color which is undesirable to most consumers.
Therefore, if the meat was butchered and packaged in a gas permeable (hereinafter "permeable") film, as is typical at retail, at a central location and then shipped to another location for eventual sale, in all likelihood, by the time the package reached the retail outlet the meat would have undergone the transformation to the brown color and would be effectively unsalable. Conversely, if the meat was butchered and packaged at a central location in a gas-impermeable (hereinafter "impermeable") film, either under vacuum or with vacuum and a low oxygen gas flush, and then shipped to another location for eventual sale, the meat would reach the retail outlet having a purple color which is typical of meat prior to exposure to oxygen. Heretofore, marketing efforts to teach the consumer about the harmlessness of the purple color have proved to be difficult. And, if the gas impermeable film was a component of a conventional package having a tray which is overwrapped or lidded with a film and which contains a low oxygen atmosphere, the impermeable film would have to be removed and replaced with a permeable film in order to allow for bloom of the meat to a bright red color prior to display for the consumer, negating to a large extent the benefits of a central processing facility.
A variety of packages have been developed in an effort to provide a means for transporting meat in a low oxygen environment and for quickly and easily introducing oxygen to the meat at the retail outlet immediately prior to display to the consumer.
One approach to solving this problem has involved the development of peelable films. That is, films have been developed which readily delaminate into permeable and impermeable portions. Such a film is sealed to a support member, such as a tray, which contains the meat product, thereby forming a gas impermeable package for distribution. At the retail outlet, the gas impermeable portions are peeled from the film leaving a permeable film sealed to the tray and, therefore, a gas permeable package which allows the meat to bloom to bright red because of the exchange with atmospheric oxygen.
The peelable film may extend over the contained product and be sealed to the periphery of the tray as a lid or it may be heated and draped over the product under vacuum to form to a vacuum skin package. Peelable films have the advantage of providing a single web for sealing to a conventional tray flange. However, peelable films often fail during peeling, with the impermeable portion either being difficult to delaminate from the permeable portion or with the all or part of the permeable portion remaining bonded to the impermeable portion and pulling away from the package product resulting in tears or pinholes in the package.
Most of the other approaches to achieving the goal of central fresh red meat processing have involved the development of a variety of dual web packages of the type having a permeable film covering the meat product and an impermeable film, which is removed at the retail outlet, covering the permeable film wherein the permeable film and the impermeable film are separate, discreet films.
Examples of these types of packages include dual overwrap packages wherein a permeable film is wrapped around the meat and its support member and an impermeable film is wrapped about the permeable film; packages with a head space which allows for the introduction of a treating gas, typically nitrogen, carbon dioxide or some mixture of the two, between a permeable film adjacent to the meat product and an impermeable upper web; and, most commonly, dual lid packages which include a permeable web and an impermeable web both sealed to the peripheral flange of the support member. One drawback of such dual web packages has been the difficulty of sealing two webs to a single conventional tray flange in an automated fashion. That is, the permeable film must be applied to the upper sealing surface of the tray, sealed about an inner periphery thereof and trimmed. The impermeable film must then be applied to the tray's sealing surface, sealed about an outer periphery thereof and trimmed. The difficulty in performing this procedure arises in the step of trimming the permeable web sufficiently to avoid interference with the peripheral flange and avoid damage to the tray detrimental to its barrier property and adversely affecting the seal between the impermeable film and the outer periphery of the tray's sealing surface. Typically, either the outer edges of the permeable web extend into the sealing area for sealing the impermeable web to the outer periphery of the flange, or the outer edges are trimmed to avoid such sealing area but the trimming step damages the tray at the flange surface because the film is lying flat against the flange when it is trimmed and the knife or cutting edge necessarily cuts into the flange.
In an effort to overcome this difficulty, a dual flange tray has been developed which includes an inner flange portion for sealing with the first or permeable web, an outer flange portion for sealing with the second or impermeable web, and a depression separating the two for trimming the permeable web thereby avoiding interference with the impermeable web seal. Such trays are disclosed, for example, in copending U.S. Ser. Nos. 08/470,283, 08/470,808, and 08/471,065. However, such dual flange trays are more costly to manufacture than conventional single flange trays and, furthermore, have the disadvantage of presenting an unfamiliar appearance to the consumer.
Thus, it is an object of the present invention to provide a package which facilitates the automated, central processing of fresh red meat with minimum expense.
It is yet another object of the present invention to provide a package which is similar in appearance to that which consumers are accustomed to seeing for meat packaging.
It is yet another object of the present invention to provide a package which may be assembled, filled and sealed at a central processing facility.